As for tuckable holsters, you will have a hard time finding holster makers that specifically list the C3. The normal Sig 1911 have a "funny" slide profile and a lot of holster makers don't have molds for those specific guns. A lot of people like the Crossbreed Supertuck...

Buy a crossbreed super tuck or one of the variants of such. There are many good quality holsters out there. The leather Kydex hybrids are very good...spread the weight out and allow almost any sized weapon to hide if worn with the proper colothing. I use a Jolster.